1. Field of the Invention
The present invention relates to a squirrel-cage rotor used for an induction motor. The present invention also related to a manufacturing method of a squirrel-cage rotor.
2. Description of the Related Art
A squirrel-cage rotor in which electrical conductive bars made of copper or copper alloy are respectively inserted through slot holes of a rotor core and opposite ends of each electrical conductive bar are joined to a pair of end rings by brazing is known. The squirrel-cage rotor described in Japanese Unexamined Patent Publication (kokai) No. 2004-254433 (JP2004-254433A) is configured to form grooves for disposing brazing filler metals on an outer end face in a rotational axis direction of the rotor of each end ring. The rotor is heated so that the brazing filler metals melt and flow into clearances between the end rings and the electrical conductive bars at the back of the grooves.
However, in the squirrel-cage rotor described in JP2004-254433, because the grooves for disposing the brazing filler metals are formed on the outer end faces of each end ring, the end rings have to be thick, and therefore material cost is increased. Further, because the grooves have to be formed, processing cost is also increased.